eglumine-based supramolecular amphiphiles: The effect of chain lengt

Author(s)

Alonso, J. D. ^[1] ; Ferreira, L. M. B. ^[2] ; Oyafuso, M. H. ^[1] ; Cassimiro, D. L. ^[1] ; Barud, H. ^[3] ; Ribeiro, C. A. ^[1]

Affiliation

^[1] Sao Paulo State Univ, Chem Inst, R Prof Francisco Degni S-N, BR-14800060 Araraquara, SP - Brazil

^[2] Sao Paulo State Univ, Sch Pharmaceut Sci, Rodovia Araraquara Jau Km 1, BR-14801902 Araraquara, SP - Brazil

^[3] Univ Araraquara Uniara, Lab Biopolymers & Biomat BIOPOLMAT, Araraquara, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF MOLECULAR LIQUIDS; v. 351, APR 1 2022.
• Web of Science Citations: 0

Abstract

Surfactants are amphiphilic substances that lower the surface tension or influence the surfaces' contact between two liquids. They are suitable for a wide range of industrial applications, often being used as emulsifiers. However, most of them are petroleum derivatives and generally are non-biodegradable. New synthetic surfactants have been reported in the literature using a covalent synthesis method, but it takes several steps and uses a large amount of toxic organic solvents. To overcome those drawbacks, we proposed a supramolecular green synthesis route. The acid-base reaction between meglumine (MEG) and two saturated carboxylic acids differing in chain size, undecanoate acid (UM, 11 carbons) and palmitic acid (PM, 16 carbons), were performed in a minimum quantity of organic solvent. The supra-amphiphiles, PM and UM, were analyzed by Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), Capillarity Viscosity, Small-angle X-ray scattering (SAXS), and Polarized Optical Microscopy (POM) in the presence and/or absence of water. We observed two distinct self-assembly behaviors in water. UM act as a surfactant since SAXS showed micellar aggregation, and its relative viscosity curve has no alteration. Additionally, the events present in DSC curves show no evidence of gel-sol transition due absence of stable hydrogen bonds. On the other hand, PM act as a supramolecular polymer, as evidenced by a baseline shift of the DSC curves due to the disruption of hydrogen bonds. Moreover, PM self-assembles in water in a liquid-crystalline arrangement with increasing viscosity in a concentration-dependent manner. SAXS studies showed the formation of lamellar and hexagonal mesophases. Based on these results, we proposed a model in which the adducts' supramolecular organization is dependent on the hydrophilic/hydrophobic balance. When it tends to the hydrophobic side, there is the formation of the supramolecular polymer. The Van der Waals interactions are necessary to organize the liquid-crystalline mesophase. Also, they are necessary to stabilize the hydrogen bonds between MEG/water, enabling the gel-sol transition, leading to new properties, like thermal reversibility observed in PM. (C) 2022 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/08411-0 - Phase behavior and themorheological properties of meglumine-based amphiphilic gels potentially aplicable as bioadhesive materials
• Grantee: Clovis Augusto Ribeiro
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/22443-4 - Supra-amphiphilic based meglumine as a strategy for modulating interactions with skin: a new approach for the treatment of inflammatory skin diseases
• Grantee: Jovan Duran Alonso
• Support Opportunities: Scholarships in Brazil - Scientific Initiation